Paleomagnetic data from the lunpola basin

The Lunpola Basin in the central Tibetan Plateau is situated along the southern margin of the east-west stretched Banggong-Nujiang suture belt between the Qiangtang Terrane and the Lhasa Terrane. The thick and continuous Cenozoic sediments in the basin can provide great potential for understanding the tectonic uplift, paleoaltimetry, erosion and depositional history of the Tibetan Plateau and climate environmental evolution. However, the study of geologic and climatic changes has been hindered by poor age constraints on the Cenozoic sedimentary sequence in the Lunpola Basin, especially its upper part with typical lacustrine oil shale sediments due to the discontinuous or unexposed outcrop caused by erosion or weathering. In this study, we investigated a 658 m-thick Cenozoic continuous lacustrine sedimentary section, Lunpori, from the upper sequence of the central basin. We found two layers of tuffs in this section and then carried out detailed paleomagnetic measurements. Constrained by tie points of U-Pb zircon ages, the observed magnetic zones are well correlated with chrons C5Bn.2n to C6AAn of the Geomagnetic Polarity Time Scale, yielding ages of ~21.2 to 15 Ma for the section. Lithofacies, pollen and fossil records suggest a relative temperate, humid climate prevailing in the Lunpola Basin during the period of Dingqinghu Formation, indicating that the Indian monsoon occurred before ~26 Ma.Through paleomagnetic analysis and testing of fluvial and lacustrine facies strata in Lumpola Basin since Miocene, 22Ma-15Ma magnetic stratigraphic chronology has been obtained.